The present invention is related to upgrading synchronously in real-time a distributed switching system without turning off traffic. More specifically, the present invention is related to upgrading synchronously in real-time a distributed switching system without turning off traffic by sending a queue resynch signal and making all switching elements act on this signal at the same logical time when this signal is received.
In a distributed switching system where multiple switching elements are processing a portion of each packet, all the switching elements have to be synchronous, i.e. executing same steps at the same logical time. This is especially relevant if packets could be dropped due to, for instance, temporary overbooking of available resources. Ordinarily, during a system upgrade where new switching elements are added or system control information need to be updated synchronously in all switching elements, all the traffic is turned off until the upgrade is complete. This is a problem in critical systems where the traffic cannot be turned off for long period. A switch which stripes data onto multiple fabrics and sends parity data to another fabric has been described in U.S. patent application Ser. No. 09/333,450, incorporated by reference herein. See also U.S. patent application Ser. No. 09/293,563 which describes a wide memory TDM switching system, incorporated by reference herein.
The present invention pertains to a switch of a network. The switch comprises port cards which receive packets from and send packets to the network. The switch comprises a switch control processor for providing control information. The switch comprises fabrics (or switching elements) for switching the packets. The fabrics receive control information from the switch control processor but all the fabrics only implement the control information at a same logical time when each fabric receives a control initiation signal from one of the port cards. Each respective fabric continuously operating on packets before, during and after each respective fabric receives the control initiation signal.
The present invention pertains to a method for switching packets. The method comprises the steps of receiving packets at a port card of a switch from a network. Then there is the step of sending fragments of each packet to fabrics of the switch. Then there is the step of distributing control information from a processor to the fabrics of the switch as the port card continues to receive packets. Next there is the step of receiving a control initiation signal from the switch control processor through the network at the port card. Then there is the step of sending the control initiation signal from the port card to the fabrics. Next there is the step of implementing the control information at each fabric only after the respective fabric receives the control initiation signal so all the fabrics implement the control information at the same time.